as "outside designed chemical specifications." MB specifies theirs or Zerex G-05.

Chemical buffers and lack of phosphoric acid are good enough reason why for me.

Outside spec. (also consider WHAT HAPPENED WHEN IT OVERTEMPS, coolant too low = steam in upper end.) Not to lecture on it all but reactions happen in the big steam pocket that would not in fluid. End result is ceramic formation, blocking heat transfer to the fluid. This can be seen in radiators with six figures of miles on them which loose the ability to cool.

Add to that the loose 'stuff' that wasn't, AND the thermostat's internal wax pellet that is now distorted and should be R&R'd.

Bottom line - if you got toward hot check it with some test strips, if you boil over you have some work to do.
***NB, If you want longevity? - When you mix to refill, use DISTILLED water (not purified or filtered) you DO NOT want to add minerals back that were taken out of the coolant.